He'll is a contraction of “he will,” used when talking about something a boy or man will do in the future. When you say “he'll arrive tomorrow,” you're saying “he will arrive tomorrow” in a shorter, more natural way.

Contractions like this can make speech and writing flow more smoothly. Instead of saying “Dad says he will help me with my project later,” you might say “Dad says he'll help me with my project later.” The apostrophe shows where letters were removed when the two words combined.

You'll see he'll used constantly in everyday conversation and in most writing except very formal documents. “He'll be here soon,” “He'll love this gift,” or “He'll understand once you explain it” all sound more natural than their longer versions.

The contraction works the same way whether you're talking about someone specific (like your brother) or someone general (like when you say “If someone works hard, they'll succeed”). Just remember: he'll usually means something hasn't happened yet but will happen later, though it can also be used for confident guesses about the present, like “He'll be in his room now.”